Physiology The oxygen-hemoglobin dissociation curve is sigmoid because A Binding of one oxygen molecule increases the affinity of binding other Oz molecules B Binding of one oxygen molecule decrease the affinity of binding other Oz molecules C Oxygen affinity of Hemoglobin decreases when the pH of blood falls D Binding of oxygen to Hemoglobin reduces the affinity of Hb for C02 💡 Explanation The oxygen-hemoglobin dissociation curve is sigmoid because ✓ Correct Answer: A. Binding of one oxygen molecule increases the affinity of binding other Oz molecules